Electric fuse and alpha method of assembling same



Oct. 4, 1932. H. T. BussMANN 1,881,351

ELECTRIC FUSE AND A METHOD OF ASSEMBLING SAME Filed Nov. 9, 1923 56.7 F/cig f76- Patented Oef. 4, 1932 PATENT OFFICE HENRY T. IBUSSMANN, F ST. LOUIS, MISSOURI ELECTRIC FUSE AND A METHOD 0F ASSEMBLING SAME Application mea November e, i923. serial No. 673,755.

My invention relates to electric fuses and refers particularly to that type of fuse known as'the renewable knife blade contact type, and the object of my invention is to provide a fuse that is simple to renew, having a minimum number of parts and yet safe in operation and capable of being renewed indefinitel l yThese advantages of my invention will be more readily understood by referring to the accompanying drawing, which shows a preferred embodiment of my invention.

Fig. l is a view of my fuse showing a longitudinal section thereof. Figs. 2 and 3 show the fuse structure. Fig. 4 shows the enclosure and Figs. 5, 6, 7, 8 and 9 show end fittings and caps, which are part of the enclosure.

In the'drawing, the fuse structure is composed of terminals 10, 11, heldin permanent relation to each other by means of a nonconducting member 12, and connectors-13, 13, therefore. The advantage of having the terminals held in this manner is very readily a parent. It reduces to a minimum the num er of parts to be handled when renewing the fuse; the terminals are always held in line so as to insure good contact with the fuse block clips and injury to the link is prevented because there is at no time, any strain on the link. I am aware of the fact that the idea of terminals held together by an insulatip ng bar is not new, but I am also aware that none of the methods hertofore shown have 5 been successful.

Fibre is preferably used for this member 12. The rapid disintegration of fibre at temperatures slightly above normal is well known. Close proximity of a fuse link when heated up to near its melting point, as it would be when carrying its' full load, would cause the libre to disintegrate. Poor Contact yof the link on the terminals or poor contact of the terminals in the fuse block clips would cause these terminals to heat up to such an extent as to rapidly .disintegrate the fibre, if the terminals were to come into contact with i this member 12. I therefore prefer to arrange this non-conducting` member 12 in such a way that it is removed as far as possible from the fuse link and so that it is held as near to the inside wall of the tube as possible. I then provide the connectors 13, 13, so as to prevent the direct transmission of the heat that might be in the terminals, to

lthe non-conducting member 12. These connectors therefore serve to hold the member 12 as far from the fuse link as possible, they serve to keep the terminals away from direct Contact with this member, and by making these connectors of lesser dimension than the terminals and of metal having a lesser thermal conductivity than the metal of the terminals, it is obvious that the amount of heat transmitted from the terminals to the member 12 is reduced to a minimum, thereby insuring long life of this member.

Fibre will shrink at temperatures slightly above normal therefore, with the member 12 made of fibre, such shrinkage would pull the terminals closer together, causing the link to buckle, possibly in the direction of the member 12. In renewing the fuse, the user might carelessly bend the link and thereby permit its center portion to come near the member 12, I therefore prefer to provide these fuses, in the sizes that require long links, With a fitting 14 preferably attached to the member 12 to keep the center of the link away from this member. This fitting may be made of insulation or of metal of low heat conductivity, so as to permit of the least amount possible of heat being transmitted to the member 12 from the link when it is in contact with this fittinglll.

The fuse link 15 may be of any desired type and is attached to the terminals by means of bolts 16, 16. By providing the link with notches 17, 17, it is unnecessary to remove `the bolts from the terminals.

the connectors. These hollow rivets permit the link holding bolts 16, to be passed therethrough and a connector holding means 1s therefore provided without taking up any additional space and yet one whichv is very substantial.

This fuse structure must be straight in line and as the non-conducting member l2 and the connectors 13, 13 are being depended upon to hold the entire structure straight, it-

is obvious that a means must be provided for connecting the terminals, connectors and nonconducting member in such a way that they will maintain a straight line. The hollow rivets 18 will not prevent the swinging out inch, until they are firmly in contact withV the washers 21, 22 attached to the terminals. Thereby they take up the slight differences in dimensions whichwould otherwise permit `the terminals to swing out of line.

The casing 23 is provided at one end with la closure 24 attached preferably on the inside of the casing by threads 25. `This closure has a` slot 26 to allow the terminal to be passed therethrough. On this closure is mounted acap' 27 held in position by suitable means such as projections produced by indentations 28 riding in the groove 29. The terminal has a washer 21 attached, which washer rests against the inside of the closure 24.

At the other end of the casing, is provided j a ring 30 attached by threads 31. Washer 32 attached to the terminal 11 is of such size as to close the opening in the ring and such washer is held in position by means of cap 33 which is attached by threads 34 to the ring. Washer 22 also attached to terminal 11 has projections 35 which seat in the grooves 36 in the ring 30 to hold the terminal in a set position. This combined with the fact that the terminal 10 rests in the slot 26 which slot is exactly 90 degrees removed from the notchesin the other ring, causes the terminals to be held in perfect alignment.

It will be readily understood from this description that in dissembling the fuse, all that is necessary is to remove the cap 33, rotate the cap 27 and remove the fuse structure. After the link is replaced the 'fuse structure is again inserted inthe casing, the cap 27 swung in position 'and the cap 33 screwed on to complete the renewal of the fuse.

surface of the ring 24 makes it impossible for this cap to stick in any way. By having the notches 36 in a metal ring at the end of the casing, much better alignment is secured, than would be the case if these notches were in the ends of the fibre. Furthermore, by having the cap 33 attached to the ring instead ofvdirectly to the fibre it is impossible for the cap to become loose if the fibre should shrink or for the cap to stick if the fibre should swell. yThe closing washers being attached directly to the terminals the handling of additional parts is eliminated and it is impossible for the fuse to be put together in any but a complete way. This is obviously very important because in renewable fuses of the ordinary type, washers are often left out of the case by Vusers with the result that such fuses become fire hazards.

In order to keep the size of the casing down to a minimum for the size of terminal used, the washer 21 must be not substantially wider than the terminal.` The fact that the washer is practically no wider than the terminal and that the aperture must be of the full width of the terminal -leaves a direct opening into the interior of thc fuse along the edge of the terminal blades. Such opening, although comparatively small, is still i sufficiently large to permit the expulsion of enough hot gases as to readily ignite infiammable material that might be near the fuse, and it is therefore necessary to provide some means to prevent this.

I accomplish this by providing the cap 27 with an opening 37 so arranged that it can be swung to engage the sides of the terminal at 38, thereby forcino' the gases that would come out along the edges of the terminal to follow an indirect path. -Or, I might arrange as shown in an alternate construction, to leave oil:` the cap 27, and provide wings 39, 39 held by pins 40, 40, or otherwise. The

wings would engage the sides of the terminal and accomplish the same result as with the cap 27.

I claim:

1. In a renewable knife blade fuse, a fibre casing, a terminal, a washer abutting on said terminal, a member having a slot within which slot the terminal is positioned, said member coacting with said washer to substantially close one end ofthe casing, and ,IFJ

threads on said member for engagement with sure engaging the slot in the terminal to hold the terminal against longitudinal movement relative to the closure.

3. In a fuse, a casing, al closure, means for holding the closure to t-he casing a terminal removably positioned within "the closure, ay

fuse link, means for holding the link to the terminal, a washer yattached to the terminal and a device on the closure co-acting with said closure and washer to prevent the direct exit of the gases generated on blowing of the fuse link. t 4. In a fuse, a. casing, a closure, means for holding the closure to the casing, a terminal, a. fuse link, means for holding the link to the terminal, a washer attached to the terminal and a cap held on the closure co-acting with said closure and washer to prevent Ythe direct eXit of the gases generated on blowing of the fuse link.

5. In a fuse, a casing, a closure permanent- 1y attached to the casing, a terminal, a fuse link, means for holding the link to the terminal, a washer attached to the terminal and a device on the closure coacting with said closure .and washer to prevent the direct exit of vapor. v

6. In a fuse, a casing, a closure adapted to permit a terminal to be passed therethrough, means for holding the closure to the casing, a terminal, a fuse'link, means for connecting vthe linkto the terminal, said closure holding the terminal against rotational movement and a device on the closure coacting with said closure adapted to prevent the exit of vapor along the edge o'it' the terminal. y

7. In a fuse, a casing, a closure permanently attached to the casing, a terminal, a fuse link connected to the terminal, said closure holding the terminal against rotational y movement, and a cap held on the closure and co-acting with said closureto prevent the exit of vapor along the edge of thelterminal.

8. In a fuse, a casing, a closure, means for. holding the closure to-the casing, a terminal, r a fuse link, means for holding the link to the terminal, a- Washer attached to the terminal,

' means for holding the terminal against rotational movement and a cap held on the closure co-acting with said closure and washv er to prevent a direct .exitof the gases4 generated on the blowing of the fuse link. 9. In a fuse, a fuse link, and a fuse structure comprising a pair of terminals, a member of insulating material and means for attaching the member to the terminals for holding them in spaced relation to each other, said structure being so constructed as to permit the link to bex positioned in a substantially straight line from one terminal to the other; and means carried by the member adapted to cause the link to bulge from the member and said means upon change in the relative lengths of said member and link.

l0. In a fuse, a fuse link, and a fuse structure comprising a pair of terminals, a member of insulating material and means for attaching the member to the terminals for holding them in spaced relation to each other, said structure being so constructed as to permit the link to be positioned in a substantially straight line from one terminal to the other; and meanscarried by the member and independent of the link, with which means the link may come in contact and thereby the distance between the link and the member be prevented from becoming less than a predetermined minimum. Y y

ll. In a fuse, a fuse link, and a fuse structure comprising a pair of terminals', a member of insulating material and means for attaching the member to the terminals for holding them in spaced relation to each other, said structure being so constructed as to permit the link to be positioned in a substantially straight line from one terminal to the other; and means carried by the member and independent of the link, with which means 'the link may come in Contact and thereby 12. rlhe hereinbetore described method of producing a rigid fuse structure comprising terminals held in permanent relation to each other by a bridge of insulating material and connectors attaching the bridge to the terminals, which consists in iitting a washer to a terminal, fastening a connector to the terminal so that one end of the connector is close to the washer and swaging the end of the connector against the washer.

13. In a fuse, a casing, a closure permanently attached to the casing, a terminal, a i'use link connected to the terminal, and a device on said closure and means inside the. closure coacting with the device on said closure to provide an indirect exit along the terminal for gases generated 0n blowing of the 'fuse link.

14C. In a renewable fuse, a casing, terminals and means for connecting a fuse link thereto, a closure attached to one end of the closure having' an opening to receivey arterminal and hold same against rotational movement, means for holding said terminal against longitudinalV movement relative to the closure, a device permanently attached to the other terminal to close the openI end `of the casing, means `rigid with said other terminal and means at the end of the casing in engagement with said last mentioned means coacting with the opening in the closure to hold the terminals in alignment and a cap holding said device in position.

15. In a renewable fuse, terminals held together by a non-conducting bar, means for connecting a fuse link to the terminals, a casing, a closure attached to one end of the casing and positioned against rotation, said closure having an opening to receive a terminal and hold same against rotational movement,v means for holding said terminal against longitudinal movement relative to the closure, a device permanently attached to the other terminal to close the open end of the casing, means rigid with said other terminal and means at the end of the casing in engagement with said last mentioned means coacting with the opening in the closure to hold t-he terminals in alignment and a cap holding said device in position.

16. In a renewable knife blade fuse, a libre casing, a terminal, a`one piece slotted device substantially closing one end of the casing and fitting about the terminal positioned in said slot, threads on the exterior of the device for engagement with threads onithe inner end of the casing, to hold the device to the casing, and to 'position the terminal against rotationalmovement." .f

17. In a renewable fuse, a casing provided with a slot at one ot its ends, terminals, means for connecting'a fuse link thereto, a closure permanently attached to vone end of 'the casing having an opening ot' suici-ent clearance to permit a terminal to be passed therethrough and to hold such terminal against lrotational movement, one of said terminals positioned in said opening, saidl terminal having attached thereto a washer to close the clearance space in the opening'on the long sides of the terminal; means attached to the other terminal to close the open end of the casing, a projection rigid with said other terminal engaging the slot at the end of the casing and coacting with the opening in the closure to hold theterminals in alignment, and a cap holding said means in' position.v

18. In a renewable fuse, -a casing, terminals, means for connecting a fuse link thereto, a closure permanently attached to one end of the casing having a slot of sufficient elearance to permit a terminal to be passed therethrough and to hold such terminal against rotational movement, one of said` terminals positioned in said slot, saidterminal having attachedthereto a washer to close the clearj ance space in the slot on the long sides of thev terminal; a washer permanently attached to the other terminal to close the open end of the casing, means rigid with said other terminal anglmeans at the end of the casing in engagement with said last mentioned means -end ot' the casing having an opening of suliicient clearance to permit a terminal to be passed therethrough and to hold ysuch terminal against rotational movement, one of said terminals positioned in--said opening, said terminal having attached thereto a device to the long sides of the terminal ya slotted cap holding member permanently attached to the other end of the casing, means'permanently attached to the other terminalto close the' open end y of the casing, a projection rigid with said other terminal'engaging the slot in the'cap holding member and co-acting with theV opening inlthe closure to hold the terminals in alignment, and a cap engaging said cap holding member to hold said means in position.

20. In a renewable fuse, acasing provided with a lslot at an end thereof, 'terminals held together by a non-conducting bar, means for connecting a fuse lin-k to the terminal, a closure permanently attached to one end of the casing having an opening of suiicient clearance to permit a terminal to be passed therethrough and, to hold such terminal against rotational movement, oneof said terminals positioned in said opening, said terminal having attached thereto a washer `to close the clearance space in the opening on the long sides of the terminal; means attached to the other terminal to close the open end of the casing and co-acting with the opening in the closure to hold the terminals close the clearance space in the Iopening on in alignment, and a v,cap holding said means j in position. L

21. In a inse, a caslng, a closure, means for holding the closure to the casing, a terminal removably positioned within the closure, a fuse link connected to the terminal, means for holding said terminal against rotational movement, a'device on the closure and means` inside the closure coacting with the device on the closure to prevent the direct exit along the terminal of gases generated on blowing ofthe fuse link..

221A renewable fuse, comprising an en-4 Lesii ing structure; said fuse structure comprising knife blade terminals, a fuse link, means for connecting the link to the terminals, and a member of insulation material-holding the terminals in spaced relation to each other, said member being positioned to avoid contact with the link, means for holding the fuse structure inthe enclosing structure; said enclosing structure comprising a casing, closure elements and means for holding the closure elements to the casing, independently of the fuse structure and independently of the fuse structure holding means; said enclosing structure being arranged to permit the assemblage of the fuse structure in the enclosing structure without rotation of one structure relative to the other.

23. A renewable fuse, comprising an enclosing structure and a fuse structure adapted to be inserted "thru one end of the enclosing structure; said fuse structure comprising knife blade terminals, a fuse link, means for connecting the link tothe terminals, and a fibre bar holding the terminals in spaced relation to each other, said member being positioned to avoid contact with the link, means for holding'the fuse structure in the enclosing structure; said enclosing structure comprising a casing, closure elements and means for holding the closure elements to the casing, independently of the fuse structure and independently of the fuse structure holding means; said enclosing structure being arranged to permit theassemblage ot the fuse structure in the .enclosing structure without rotation of one struct-rre relative tothe other,

24. renewable fuse, comprising an enclosing structure and a fuse structure adapted to be inserted thru oneend oit the enclosing structure; said fuse structurecomprising knife blade terminals, a fuse link, means for connecting the linkto the terminals, and a member of insulation material holding the terminals in spaced relation to each other, spacing members holding the member of insulation material away from the 'terminals andlink, means for holding the fuse structure in said enclosing structure; said enclosing structure comprising a casing, closure elements and means for holding the closure elements to the casing, independently of the iluse structure and independently of the fuse structure holding means; said enclosing structure being arranged to permit the assemblage of the fuse structure in the enclosing structure without rotation of one structure relative to the other.

25. A renewable fuse, comprising an enclosing structure and a fuse structure adapted `to be inserted thru one end of the enclosing structure; said fuse structure comprising knife blade terminals, a'fuse link, means for connecting the link to the' terminals, and a ibrebar holding the terminals in spaced relation to each other, Spacing members holding the bre bar away from theterminals and link, mea-ns for holding the fuse structure in the enclosing structure; said enclosing-structure comprising a casing, closure elements and means for holding the closure elements to the casing, independently of the fuse structure and independently of the fuse structure holding means; said enclosing structure being arranged to permit the assemblage of the :tuse structure in the enclosing structure without rotation of one structure relative to the other.

26., A renewable fuse, comprising an enclosingstructnre and a fuse Structure adapted to be inserted thru one end of the enclosing structure; said fuse structure comprising knife blade terminals, a fuse link, means for connecting the link to the terminals, and a member of insulation materialholding the terminals in spaced relation to each other, said member being positioned to avoid contact with the link, means for holding the fuse structure in the enclosing structure; said enclosing structure comprising a casing, closure elements and means vfor holding the closure elements to the casing, independently of the fuse structure and independently of the Jfuse structure holding means; said closure elements co-acting with means on. the terminals to limit longitudinal movement of the terminals independent of the member; said enclosing structure being arranged topermit the assemblage of the fuse structure in the enclosing structure without rotation ot one structure relative to the other.

27, ln an electric fuse, a tubular shell; a fuse-element and use-element-holder assembly, including knife-blade terminals, located in said shell and removable therefrom as a unit; and means permanently located on thel shell for positively securing said unit in the shell without subjecting the unit to torsional strains.

28, ln a renewable fuse, 'terminals held together by a non-conducting bar, means `for connecting a fuse link 'to the terminals, a

lminal against longitudinal movement relative to the closure.

29. ln a renewable fuse, terminals, means for connecting a fuse link to the terminals, a casing, a closure permanently attached to one end oi the casing and positioned against rotation, having an opening within which one of the terminals is removably positioned and held against rotational movement and means on the closure for holding the terminal against y 'longitudinal movement relative to the closure.

30. In a renewable fuse, terminals, means for connecting a fuse link to the terminals, a casing, a closure permanently attached to one end of the casing and positioned against rotation, having an opening Withiny which one of the terminals is removably positioned 10 and held against rotational movement and a cap held on said closure adapted to hold said terminal against longitudinal movement relative to the closure.

31. In a renewable fuse, a link, terminals,

a support for holdingsaid terminals in fixed spaced relation to each other,v a fastening device passing thru said' terminal for attaching said support to one of said terminals and a link holding device extending through 420 said fastening device for detachably connecting said link to one of'said terminals.

n 32. In a renewable fuse, a casing, a terminal, a closure, threaded engagement means for holding said closure-to said casing, and

` a transversely movable device outside the closure engaging the terminal to limit the inward longitudinal vmovement of the terminal rela-v tive to the casing. y

i HENRY. T. BUSSMANN. 

